It is common to produce both tubing and formed shapes in a continuous process. Both tubing and various shapes can be either extruded or continuously formed from flat stock using a rolling or shaping process followed, in many cases, by a seam welding process. At the end of the manufacturing line one typically finds a cutoff of the flying shear type. Essentially a flying shear comprises a base, a carriage mounted on the base for reciprocal movement along a path which is parallel to the path of movement of the stock to be cut, a motive power source such as an air/oil accelerator for reciprocating the carriage between extended and retracted positions and a subassembly such as a die set mounted on the carriage and operable through a reciprocating cycle to shear and withdraw from the stock during the forward motion of the carriage.
A typical cutoff press which has been popular for many years in the tubing industry comprises a base supporting a large motor-driven flywheel whichh is actuated by means of a clutch assembly to transfer mechanical energy to a ram which in turn reciprocates a shearing die set on command. A substantial brake mechanism must be employed in addition to the clutch mechanism to stop the ram and the associated crankshaft at the conclusion of each cycle of operation. In addition to the motor and flywheel for driving the ram, a second independent motive power source such as an air/oil accelerator is utilized to drive the die set along an arrangement of die carriage rails so as to bring the die shearing carriage up to synchronous speed with the stock before initiating the cut. See for example the patents to Alexander Borzym, U.S. Pat. No. 22,114 and U.S. Pat. No. 3,273,433 as examples of flying cutoffs using multiple power sources.